Recently, with popularization of computers, an optical disk, a magnetic disk, a magneto-optical disk and the like have become popular and miniaturized, and further, with development of image-signal digital processing techniques, “compression-encoding” processing can now be performed with respect to image data without serious degradation of image quality. One example implementation of use of such image processing techniques is a camcorder having one of the above-mentioned mass-storage arrangements. In the magnetic disk, the optical disk, the magneto-optical disk and the like, data such as the aforementioned image data can be stored thereon, and such data may be managed as files. Although practice of the present invention is not limited thereto, the following discussions will focus on examples using a magneto-optical disk to record image (e.g., video) data. However, it should be remembered that such focus is made only for the sake of brevity/conciseness of this disclosure.
For file management, files may be arranged according to a logical structure having a management data and a file data part, with a predetermined number of bytes constituting a sector and a predetermined number of sectors corresponding to the logical structure. A command of recording, reproduction or deletion of a file may be inputted and conducted with respect to the magneto-optical disk. When the command of recording, reproduction or deletion is inputted, data is recorded, reproduced or deleted with respect to a file area of the disk.
With regard to problems to be solved by the invention, in a disadvantageous file management arrangement, when data is to be recorded as a file, file data is recorded in a data recording area, and then management data is recorded in corresponding management (e.g., directory and file name/size) area on the disk. More particularly, attention is directed to the recording operation flowchart 500 of FIG. 5, wherein after a start block 502, flow moves to a block 504 where a predetermined amount of sectors of file data are recorded onto a recording medium. At a block 506, it is determined whether recording of file data onto the recording medium has been finished, and if not, flow moves through loop 508 and again to block 504 to conduct additional recording of file data. Once it is determined within block 506 that recording of file data has been finished, flow moves to a block 510 wherein a bitmap of recorded sectors on the recording medium is updated, then to a block 512 wherein file management data on the recording medium is updated, and finally, flow is ended at an end block 514. The bitmap may have bits in one-to-one correspondence to available sectors on the recording medium, and may have a first logical value (e.g., a logical “1”) written within bitmap bits where data has been written into a corresponding recording medium sector, or a second logical value (e.g., a logical “0”) written within bits where data has not been written into a corresponding sector.
In the above recording method, for example, if a disturbance (e.g., a fault of power loss, a mechanical shock due to droppage, vibration) occurs in the apparatus before the blocks 510 or 512 are performed, file management data on the recording medium will not be updated to match the file data which has been newly written, and accordingly, the recording medium's file management information and file data will be mismatched, and a data and/or system error may occur if the faulted recording medium is attempted to be read/reproduced. Such problem is especially likely to occur in image recording apparatuses, where the above “compression encoding” processing may be performed, for example, for long term processing/recording for a video image on a tape capable of holding a video of about 80 minutes long. That is, since file data with respect to the video image is recorded for substantially long bursts of time (e.g., 5–10 minutes) with a camcorder before the management data is updated, if a disturbance occurs (e.g., power loss, mechanical shock, vibration, etc), a substantial amount of recorded file data may be lost, i.e., lost because of non-updated/mismatched management data.
As further limitations which may contribute to the fault potential, physical and processing limitations of the recording apparatus and/or the compression/recording processes may prevent the management data from being updated more frequently. More particularly, the file data area and the management data area on the recording medium may be physically separated from one another, such that a substantial amount of time may be required to move a recording head from one area to the other, preform recordation, and then move back again. In direct opposition, image data compression and recording may be an extremely time/processing intensive operation requiring substantially uninterrupted use of the recording head for recording at the file data area, i.e., time/processing requirements may be so intensive that there may be insufficient time to move the recording head from the file data area to the management data area, perform management data updating, and then move the recording head back to the file data area, without suffering substantial image data loss.
As a result of all of the foregoing, the above-described problem that data being recorded upon occurrence of fault cannot be read is highlighted.
Art of possible interest with respect to the present invention includes Japanese Patent Application Laid-Open No. 9-167447. Such technique provides an arrangement which allows determination of the existence/absence of a recording abnormality. However, with such technique, content of data management information cannot be read, and further, recorded data recorded before the abnormality cannot be recovered as a readable file.